. >> reporter: the use of drones has grown 700% under the obama administration. we learned just yesterday, that america has a secret base in saudi arabia, used to launch drones throughout the region. lawmakers will also raise questions about a newly-discovered document saying, american citizens tied to al qaeda can be killed if a high-level official believes the target poses an imminent threat. but the government can do so without having clear evidence. human rights advocates disagree. >> that justifies, essentially, a claim that the executive branch can be judge, jury and executioner. >> reporter: drone strikes have become controversial. in pakistan alone, there have been more than 300 drone strikes in the last decade, killing thousands of terrorists, but also more than 300 civilians. the retired general who once ran the military's drone strike program, thinks there should be discussion about their use. >> if the threshold gets too low and we're too casual about it, then we'll forget how much scar tissue we build up in those countries. >> reporter: the white hou